[Rover]

To be honest, the Sony and Canon 50/1.8 are at least adding one aspherical element each to the design, like the Nikon 50/1.8 G did. That might stand for something, but at the heart, they're still harking from the Belle Époque. But not all 50/1.8 have to be the same, so I don't understand the notion that a lens with these parameters just absolutely has to be small, cheap and simple in construction.

[Brightcolours]

The point was that it makes little sense to say "is designed for superior mobility", while it actually is designed for better wide open across the frame sharpness.
Said Canon and Sony are "designed for superior mobility" (and in case of the Canon, to provide a very affordable option), not necessarily for state of the art wide open across the frame sharpness.

Or you could argue as Panasonic that their MFT primes are "designed for superior mobility". It makes sense there.

[thxbb12]

Personally, I never care for what manufacturers write in their product announcements: they are just marketing blurbs that are, more often than not, meaningless.

[Rover]

As far as the Panasonic, or indeed the entire L-mount, lineup goes, it really is as lightweight as it gets at 50mm. 300 grams is the same as the Canon 35/1.8 which is, whatever way you slice it, a very compact lens.

But thxbb12 is right, what the marketing people write is largely irrelevant. They might've never held the lens in their hands, anyway.